A plasma display panel is generally provided with at least a first and a second array of coplanar electrodes, the general directions of which are parallel, where each electrode Y of the first array is adjacent to an electrode Y′ of the second array, is paired with it and is intended to supply a set of discharge regions, and comprises, for each discharge region supplied:                a conducting region Za called a discharge ignition region, which comprises an ignition edge facing the said electrode of the second array;        a conducting region Zb called a discharge expansion region, located to the rear of the conducting ignition region on the opposite side from the said ignition edge; and        a conducting region Zc called a discharge stabilization or end-of-discharge region lying to the rear of the conducting expansion region, which comprises an end-of-discharge edge that delimits the said element on the opposite side from the said ignition edge.        
The definition of these three regions will be supplemented later on in relation to the displacement of the cathode sheath.
These electrode plates are used for the manufacture of conventional plasma display panels of the type comprising a coplanar-discharge electrode plate 11, of the type mentioned above, and another electrode plate 12 provided with an array of address electrodes, leaving between them a two-dimensional set collecting the said discharge regions that are filled with a discharge gas.
Each discharge region is positioned at the intersection of an address electrode X and a pair of electrodes Y, Y′ of the coplanar-discharge electrode plate; each set of discharge regions supplied by any one pair of electrodes corresponds in general to a horizontal row of discharge regions or subpixels of the display panel; and each set of discharge regions supplied by any one address electrode corresponds in general to a vertical column of discharge regions or subpixels.
The arrays of electrodes of the coplanar-discharge electrode plate are coated with a dielectric layer 13 in order to provide a memory effect, the said layer itself being coated with a protective and secondary-electron-emitting layer 14, generally based on magnesia.
The adjacent discharge regions, at least those that emit different colours, are generally bounded by horizontal barrier ribs 15 and/or vertical barrier ribs 16, these ribs generally also serving as spacers between the electrode plates.
The cell shown in FIGS. 1A and 1B is of rectangular shape—other cell geometries are disclosed by the prior art—and the largest dimension of this cell extends parallel to the address electrodes X. Let Ox be the longitudinal axis of symmetry of this cell; at each discharge region supplied by a pair of electrodes, which forms a discharge cell, the electrode portions or elements Y, Y′ bounded by the barrier ribs 15, 16 have here a constant width measured along the direction perpendicular to the Ox axis.
The walls of the luminous discharge regions are in general partly coated with phosphors that are sensitive to the ultraviolet radiation of the luminous discharges. Adjacent discharge regions are provided with phosphors that emit different primary colours, so that the combination of the three adjacent regions forms a picture element or pixel.
During operation, to display an image, for example a video sequence:                by means of the array of address electrodes and one of the arrays of coplanar electrodes, each row of the display panel is addressed in succession by depositing electrical charges on the region of dielectric layer of each discharge region of this row that has been preselected and the corresponding subpixel of which has to be activated in order to display the image; and then        by applying series of sustain voltage pulses between the electrodes of the two arrays of the coplanar-discharge electrode plate, discharges are produced only in the precharged regions, thereby activating the corresponding subpixels and allowing the image to be displayed.        
FIG. 15 of document EP 0 782 167 (Pioneer) and FIG. 3A below show a coplanar-discharge electrode plate of the type mentioned above in which, in each discharge region supplied via a pair of electrodes, each electrode of this pair comprises an element in the form of a T comprising a transverse bar 31 facing the other electrode and a central leg of constant width 32, each electrode element being electrically connected via a conducting bus 33 via the foot of its central leg.
Each transverse bar 31 of an electrode element forms a discharge ignition region Za, each central leg 32 forms a discharge expansion region Zb and each transverse bar 33 can form a discharge stabilization region Zc. In operation, during the sustain phases, each discharge starts at one of the edges, called the ignition edge, of the transverse bar 31 and then extends along the corresponding leg 32 as far as the bus 33 to which it is connected.
A variant of the T shape is shown in FIG. 14 of the same document EP 0 782 167 (Pioneer). This is in the form of an upside-down U that has two side legs (instead of one central leg) that are perpendicular to the same transverse ignition bar as previously, which are each connected to one end of this bar. After ignition, the discharge subdivides and then extends along two parallel lateral expansion paths each corresponding to one leg of the upside-down U, the two paths joining up at the conducting bus of the electrode.
According to another variant described in document EP 0 802 556 (Matsushita), especially in FIG. 9 and reproduced in FIG. 4A below, each lateral leg of the U, 42a, 42b, is shared between two adjacent cells and the transverse bars of the elements of the same electrode form a continuous conductor, in such a way that each coplanar electrode takes the form of a ladder, a first rail of which serves as an ignition region Za, the rungs of which are positioned at the limit of the discharge region and serve as discharge expansion regions Zb, and a second rail of which serves as a stabilization region Zc.
Such a process for spreading the discharges along an expansion region forming an electrode portion is favourable to the efficiency of ultraviolet radiation production from the discharges and to a wider distribution over the surfaces of the excited phosphors.